I ph'd some well water to 6.9 and poured a gallon thru one of these quirkles, runoff was 6.8, 1550 tds, and 775 ppm according to my Hanna.
A couple other strains look great, but these quirkles aren't growing much. I did find a few spider mites about a week ago, and sprayed with Safer 3 in 1...